The present system relates generally to brake control systems and more specifically to a controller for an equalizing reservoir of a rail brake system, which includes a brake pipe controlled by a relay valve in response to pressure in the equalizing reservoir.
Prior rail brake systems have had either fully-pneumatic control of the equalizing reservoir (ER) or electro-pneumatic control of the ER. On systems which use fully-pneumatic ER control, penalty brake applications were created by exhausting a previously pressurized penalty pipe. This caused a subsequent pneumatic exhaust of the ER and brake application. On systems which use electro-pneumatic ER control, penalty brake applications are signaled to the brake system by electrical signals. The ER is then reduced to apply the brakes via electro-pneumatic control. Prior brake systems including ER controllers are illustrated in U.S. Pat. Nos. 6,036,284 and 6,318,811.
To limit the penalty reduction of the equalizing reservoir, prior systems have used reduction limiting reservoirs. Penalty application valves connect the reduction limiting reservoir to the equalization reservoir for a penalty and cuts off the control from the brake valve. The pressure in the equalizing reservoir is reduced until the two reservoir stabilize. After termination of the penalty, control is transferred back to the brake valve and the reduction limiting reservoir is emptied. Two such systems are shown in U.S. Pat. Nos. 3,623,777 and 4,491,372
A control system which allows electro-pneumatic control of an equalizing reservoir with the capacity to create penalty applications in a purely pneumatic manner is described in U.S. Pat. No. 6,746,087. The controller for the equalizing reservoir includes an electro-pneumatic source of pressure or atmosphere responsive to an electrical equalizing pressure control signal and a pilot valve selectively connecting the electro-pneumatic source or atmosphere to the equalizing reservoir in response to pressure in a pilot port of the first pilot valve. A magnetic valve is provided having a first input connected to a second source of pressure, a second input connected to atmosphere and an output connected to the pilot port of the first pilot valve. At least one penalty valve is connected to the pilot input of the first pilot valve and is responsive to a penalty signal to connect the pilot input to atmosphere. The pilot valve and the penalty valve pneumatically produce a brake application regardless of the state of the magnetic valve or its controller.
The present control system allows electro-pneumatic control of ER but with the capacity to create penalty applications in a purely pneumatic manner and reduction limiting. A controller for an ER includes an electro-pneumatic source of pressure or atmosphere responsive to an electrical equalizing pressure control signal and a first pilot valve selectively connecting the electro-pneumatic source or atmosphere at a first input or a second input to the equalizing reservoir in response to pressure in a pilot port of the first pilot valve. A magnetic valve is provided having a first input connected to a second source of pressure, a second input connected to atmosphere and an output connected to the pilot port of the first pilot valve. At least one penalty valve is connected to the pilot input of the first pilot valve and is responsive to a penalty signal to connect the pilot input to atmosphere. A fourth valve has a first input connected to the second input of the first pilot valve and an output connected to a third source of pressure lower than pressure in the equalizing reservoir prior to a penalty signal. The fourth valve connects its first input to its output in response to a penalty signal.
A method is disclosed for controlling pressure for an equalizing reservoir of a rail brake system which includes a brake pipe controlled by a relay valve in response to pressure in the equalizing reservoir and which includes an electro-pneumatic source of pressure or atmosphere having a closed loop system responsive to an electrical equalizing pressure control signal. The method includes measuring pressure in the equalizing reservoir after a penalty reduction of reservoir pressure; initially setting the electrical equalizing pressure control signal to the measured equalizing reservoir pressure after a penalty; and subsequently the activating closed loop system of the electro-pneumatic source of pressure or atmosphere to control the pressure of the equalizing reservoir to the electrical equalizing pressure control signals.
These and other aspects of the present invention will become apparent from the following detailed description of the invention, when considered in conjunction with accompanying drawings.